On the expanding universe?

[GordonHide]

They say that the rate at which the universe is expanding is increasing. And yet the stuff really far away seems to be moving much faster than the stuff not so far away. Given that that which is further away is also that much more distant in time, why does this not mean that the rate of expansion is slowing down? Would somebody not quite so obtuse explain it to me please?

[steenkh]

If for instance we look at something that is, say 1G light years away, and the universe expands so that it moves away at, say, 0.1 light year/year, then the same expansion rate would mean that something that is 2G light years away will move away at at rate of 0.2 light year/year.

You add up the expansion rate for every unit of distance to give the actual speed.

That is at least how I understand it.

[GordonHide]

Originally Posted by steenkh

If for instance we look at something that is, say 1G light years away, and the universe expands so that it moves away at, say, 0.1 light year/year, then the same expansion rate would mean that something that is 2G light years away will move away at at rate of 0.2 light year/year.

You add up the expansion rate for every unit of distance to give the actual speed.

That is at least how I understand it.

I can accept that things further away have an apparent faster speed but what that means to me as that things in the past, (and further away), were moving faster than they probably are now, (although I accept that we can't know that). We can infer it, however, from the speed of stuff that's closer, (and not so far in the past).

[steenkh]

Originally Posted by GordonHide

I can accept that things further away have an apparent faster speed but what that means to me as that things in the past, (and further away), were moving faster than they probably are now, (although I accept that we can't know that).

If light did not have a speed but was instantaneous transfer of information, and still had the redshift, then apparent speed would still be faster for more distant objects. Now we really see them in the past, but the apparent speed would be the same. We cannot know from the redshift alone if that is because the expansion rate was always the same, or if the speed changed along the way.

There was a recent article about cosmological redshift in Scientific American. I will see if I can find it.

[ShazaamsCape]

here is a newer article that could be of assistance for you GordonHide:

http://www.opfocus.org/index.php?topic=story&v=8&s=4

"First of all, it was observed by Hubble at the beginning of the XX century that galaxies appear to be moving away from the Earth at a velocity that is proportional to their distance from us. The standard explanation is that galaxies are being thrown apart from the expansion of space-time. Imagine drawing some red spots on a balloon and inflating it, the spots (galaxies) would recede from each other at a speed proportional to their distance due to the dilatation of the plastic (space-time). The drawback of this hypothesis is that it needs to postulate the existence of the famous dark matter, which has never been observed and would still constitute 70% of the Universe’s mass. However, if c were decreasing over time, the Hubble effect would turn out to be a simple optical effect, eliminating the need to postulate the existence of the dark matter, as proposed by P. I. Wold back in 1935 [1]. "

[steenkh]

Originally Posted by ShazaamsCape

"The drawback of this hypothesis is that it needs to postulate the existence of the famous dark matter, which has never been observed and would still constitute 70% of the Universe’s mass."

That is wrong: dark matter has nothing to do with the expansion of the universe. Dark matter was discovered when it was found that the rotation of galaxies implied more mass than than could be inferred from the visible mass.

The author is probably confusing dark matter with dark energy which is the energy that drives the expansion, also (if I remember correctly) represented by the cosmological constant. Dark energy is also responsible for the virtual particles that pop in and out of existence all the time.

[GordonHide]

Originally Posted by steenkh

If light did not have a speed but was instantaneous transfer of information, and still had the redshift, then apparent speed would still be faster for more distant objects.

How can we possibly know what speed far distant objects are moving at today? Wouldn't we have to have instantaneous transfer of information?

[ShazaamsCape]

Seems that light is actually slowing down.

[steenkh]

Originally Posted by GordonHide

How can we possibly know what speed far distant objects are moving at today? Wouldn't we have to have instantaneous transfer of information?

Apparently not, because it has been possible to show that the rate of expansion has slowed down, but right now I cannot explain how. Maybe I can look it up tomorrow.

[xcept2010]

Originally Posted by steenkh

Apparently not, because it has been possible to show that the rate of expansion has slowed down, but right now I cannot explain how. Maybe I can look it up tomorrow.

And how is this relevant to the discussion? Sounds like backpeddling to me. Are you afraid of not finding the right answer? Because it really seems like that's what you are doing.

okay I was only messin with you as usual. Perhaps you will stop censoring my posts and post the good ones along with the bad ones. kay.. thanks.